Treadmill training in a virtual environment showed small differences in joint kinematics compared with overground walking, supporting the continued use of virtual reality based treadmill training aimed at improving overground walking in patients with transtibial amputation, according to a recently published study.
However, mean step length and mean step time, as well as step width variability, differed significantly. Caution should be used when making comparisons of these measures between studies utilizing a treadmill and those in which participants walked overground.
“While the task of walking should, in theory, be mechanically equivalent on treadmills and overground, some data suggests that there are differences, including altered kinematics, kinetics and energy costs. Previous researchers have speculated that differences might be caused by various factors including: differences in compliance of the walking surface, subtle intra-stride variations in treadmill belt speed, the constraint of treadmill — narrow belts and railings — and unfamiliarity of walking on a treadmill. Others suggested that differences may arise from the altered sensory feedback encountered on a treadmill,” the researchers wrote. “The purpose of this study was to determine if there were kinematic or temporal-spatial differences between overground walking and treadmill walking in a computer assisted rehabilitation environment in healthy control [participants] or in individuals with transtibial amputation.”
Overground vs. CAREN
Researchers enrolled seven patients with traumatic transtibial amputation (TTA) and 27 healthy controls. Participants underwent biomechanical gait assessment both overground and during treadmill walking in a computer assisted rehabilitation environment (CAREN) system (Motek, Amsterdam, Netherlands). The CAREN system, comprising a 7-m diameter dome with a virtual environment projected 300° around the participant, applied optic flow at the same speed that the participants walked. Researchers collected temporal-spatial parameters, full body kinematics and kinematic variability during all trials.
Study results showed that both groups decreased step time, whereas control participants decreased step length when walking in the virtual environment. Both groups also exhibited increased step width variability during treadmill walking in the CAREN system. However, only minor changes in kinematic variability were observed. According to the researchers, differences in lower extremity kinematics were small and did not exceed the minimal detectable change value for these measures. Compared with patients with transtibial amputation, control participants exhibited decreased transverse and frontal plane range of motion of the pelvis and trunk when walking in the CAREN system.
“Overall, we found that the walking was similar for overground and treadmill. There were some small differences in [the participants’] walking patterns, but they were less than a couple of degrees so it was within range of measurement error that you get from the camera systems,” Deanna Gates, PhD, assistant professor at the University of Michigan, told O&P Business News.
Gates added that it was surprising how similarly the patients with TTA walked overground and on a treadmill.
“Another study looked at a little bit more impaired population and found that their energy costs were much higher when walking on a treadmill than walking overground,” she said. “So we expected some differences in the way that the patients adjusted to the treadmill since it forces them to walk at a constant speed, but we did not see any difference.”
These study results support the hypothesis that gait training on a treadmill would help create a good transition to walking overground, so patients may have less difficulty performing daily tasks. Gates and colleagues concluded that if a patient’s gait can be effectively changed during treadmill training, then it should carry over to walking overground.
“There is validity in training on treadmills because you can confine things to a very small space, you can control the visuals that [the patient] is seeing and you can add different safety measures,” Gates said. “You can also use them for making comparisons. If you were testing out different devices, you could make those comparisons on a treadmill and expect that you would see similar differences when they are walking overground.”
“What we are trying to do at this point is leverage these findings now that we have a sound understanding how individuals with TTA can walk overground and on a treadmill,” Jason Wilken, PhD, MPT, of the department of orthopaedics & rehabilitation at the Center for the Intrepid at the Brooke Army Medical Center, told O&P Business News. “Given that understanding, we are confident in implementing training programs in our virtual reality system.”— by Casey Murphy
Disclosure: Gates and Wilken have no relevant financial disclosures.